The present invention relates to an audio system, and particularly to a level control circuit for low and medium sound which produces a low and medium sound level being controlled automatically among audio signals.
In general, an exclusive speaker for low and medium sound is installed in an audio system to improve the sound quality of an audio signal which is provided to the speakers. Also, it is necessary for the exclusive speaker to be driven by the low and medium sound signal which is detected from the audio signal.
As such, the conventional level control circuit for a low and medium sound signal is such that the applied audio signals are shaped in a buffer and then amplified the shaped signal through an amplifier, and provide this signal to the speakers located on the left and the right side.
The left and right audio signals which are provided for driving the speakers are added by an adder, the low and medium sound signal is filtered from the added audio signals by a low pass filter. This filtered low and medium sound signal is amplified by a LPF signal amplifier. Finally, the amplified low and medium sound signal drives the exclusive speaker for low and medium sound.
In the conventional level control circuit for low and medium sound, however, the level for low and medium sound may be controlled only by a manual control where the selection and gain control of the low and medium signal output is performed by an external volume control. Accordingly, a user should control the low and medium signal output in everything to get a low and medium sound effect.